Method of producing butadiene from alcohols



Patented Aug. 1, 1950 METHOD OF PRODUCING BUTADIENE FROM ALOOHOLS ArnoBrasch, New York, N. Y., assignor, by mesne assignments, to ElectronizedChemicals Corporation, a corporation of Delaware No Drawing. ApplicationOctober 9, 1945, I Serial No. 621,368

1'1 Claims.

My present invention relates to methods of producing butadiene and isdisclosed in my prior U. S. patent applications Serial No. 442,136,filed May 7, 1942, which has become abandoned, for Method ofManufacturing Synthetic Rubber and Devices Therefor; Serial No.

442,137, filed May 7, 1942', which/has become Patent Number 2,429,217,for Devices for Treatment of Matters with High Speed Electrons; SerialNo. 442,138, filed May 7, 1942, which has become abandoned, for Methodfor Treatment of Matter; Serial No. 450,923, filed July 14, 1942, whichhas become abandoned, for Method and Means for Treatment of PerishableSubstances andjProducts so Obtained; Serial No. 451,370, filed July 17,1942, which has become abandoned, for Method and Means for Treatment ofVegetative Substances and Products so Obtained; Serial No. 487,179,filed May 15, 1943, which has become abandoned, for Process for CrackingHydrocarbons by Means of Ultra High Speed Electrons; and Serial No.488,278, filed May 24, 1943, which has become abandoned, for Preparationand Cracking of Hydrocarbons and Other Chemical Compounds by Means ofUltra High Speed Electrons to Obtain Rubber Starting Materials.Accordingly, this application is a continuation in part of the aboveapplications.

It is an object of my present invention to produce butadiene fromalcohols in a simple inexpensive way.

It is a further object of my present invention to produce butadiene fromalcohols by methods by which a great proportion of the alcohols used asinitial materials is transformed into butadiene.

Still another object of my present invention consists in methods ofobtaining butadiene without use of very high temperatures and/orpressure as commonly employed in the known processes of this type andwithout use of the rather expensive active catalysts used up to now forthese purposes.

With the above objects in view, my present invention mainly consists inproducing butadiene from alcohols comprising the steps ofdehydrogenating and dehydrating the alcohol serving as initial materialby treating, i. e. bombarding it with high speed electrons whereby thealcohol is decomposed and butadiene is formed.

The term high speed electrons, as used above and in the followingdescription and claims, is intended to define electrons of a velocityequivalent to more than one million volts. Preferably,

however, high speed electrons 01 a velocity equivalent to more than twomillion volts are employed for the processes of producing butadiene inaccordance with my present invention.

In accordance with a preferred embodiment of my present invention, Itreat, 1. e. bombard the alcohol repeatedly during consecutive periodswith high speed electrons in such a manner that each of these repeatedtreatment periods lasts less than preferably about 10- of a second. Ihave found that by using such short treatment periods it is possible toavoid almost entirely the formation of undesired by-products whichconstitute a basic disadvantage of all known processes.

I wish also to stress that it is advisable to use high speed electronsof a velocity equivalent to more than one, preferably two million volts;such high speed electrons have such a high energy that they are able tocause the desired decom position of the electron bombarded alcoholwithin the extremely short periods mentioned above.

I have found that treatment of an alcohol in the way proposed by meresults in decomposition of the electron bombarded alcohol intomonoolefines from which in turn di-olefines, mainly butadiene, areformed.

More particularly, if ethyl alcohol is used as initial material, thesame is dehydrogenated to ethylene; from this ethylene by subsequentconjuncture of the molecules butadiene is formed.

The electron bombardment of the alcohols as proposed by me can becarried out at room or slightly raised temperature by which all unwantedside reactions are avoided which are due in commonly used processes tothe fact that the same have always to be carried out at temperaturesabove 800 C.

For example, in accordance with the present invention, it is possible todehydrate and dehydrogenate ethyl alcohol by bombarding the same withhigh speed electrons as proposed above at a temperature between and C.,thus substantially reducing the amounts of byproducts obtained duringusual dehydration and dehydrogenation processes. The main reactionproducts obtained by such electron bombardmerit consist of butadieneand, other valuable by-products formed by the interaction of diolefinesand/or olefines, more particularly of aromatic compounds such astoluene, xylene, phenol, and others. Contrary thereto, in processes usedat the present time on a commercial scale, more than twenty otherby-products are formed during production of the butadiene, most of themcontaining oxygen and being practically valueless.

I have found that by dehydrating and dehydrogenating alcohols as setforth above, it is possible to obtain a yield of butadiene amounting tosubstantially more than 40% of the theoretically determined maximalyield. In addition thereto, up to 50% of the exit gases consist o1oleflnes, mainly ethylene, which can be recycled and subjected torepeated electron bombardment so as to transform part of the same alsointo butadiene. Thus, it is possible to obtain by electron bombardmentof the alcohol serving as initial material and of the recycled ethylene,a yield of butadiene amounting up to 60% of the theoretically determinedmaximal yield.

It should also be stressed that the butadiene obtained by the methodsproposed by me above is, due to its comparatively low content ofbyproducts, of very high purity.

- The above mentioned high yield of butadiene obtainable by electronbombardment of alcohol as proposed above is mainly due to the fact thatit is possible to apply and control the high speed electronic energyused for decomposition, i. e. dehydration and dehydrogenation of thealcohol in such a manner as to carry out the decomposition selectively,namely to obtain only or mainly the desired compounds without undesiredby-products.

The very low proportion of undesired oxygencontaining by-productsobtained by the present process can be explained by the fact that theactual impact of high speed electrons in the formation of butadiene fromalcohols is reduced to a minimal fraction of the time as compared withstandard pyrolytic processes. The chance of interaction of theunsaturated compounds with the oxygen present is consequently reduced toa minimum. Thus, unsaturated aldehydes, alcohols, ketones, etc. as wellas their saturated analogs are practically absent. Furthermore, themethane and ethane content of the exit gases is markedly reduced; sinceboth these compounds are not utilizable for the preparation of anyuseful intermediates, this constitutes an appreciable improvement.

The reaction mixture obtained by electron bombarding the alcohols asexplained above is then freed by well-known procedures of butadiene andof the desired aromatic lay-products. The remaining reaction mixture canthen be recycled and yields another 20 to 25% of butadiene and valuableby-products. It might be advisable to add to the recycled part ofthereaction mixture before recycling fresh alcohol, thus increasing theeffect of electron bombardment upon the recycled mixture.

In my above described processes, the alcohols are electron bombarded inabsence of catalytic substances. Since catalytic substances of the typeused at present for processes of producing butadiene from alcohols arehighly expensive, the possibility to avoid such catalysts is of greatadvantage and importance.

However, I have found that it is of great im portance to be able toregulate the length of the reactions caused by the electron bombardment,particularly in case of consecutive short electron bombardments lastingeach only a fraction of a second. It is evident that no particularadvantages would be attained by bombarding the alcohols with electronsduring separate extremely short periods it between these short periodsthe V 231cc started reactions would automatically con- In order to beable to regulate the length of the single reactions periods, I havefound it advisable to add, e. g. to admix to the alcohols to be electronbombarded a small percentage of agents which are adapted to prevent orat least to retard continuation of the reactions caused by electronbombardment after discontinuation and termination of the same. I havefound that such materials called by me contact materials" have a doubleeffect, namely they not only retard continuation of the reactions aftertermination of the electron bombardment, but they also facilitate andexpedite the reaction during such electron bombardment, without beingthemselves catalyticallyactive.

I have found that for the purposes of my present invention I may verywell use as contact materials various metal oxides which are not onlyinexpensive but also available in large amounts. Particularly adapted ascontact materials for the processes proposed by me are oxides of themetals of the second, third and fourth groups of the periodic system, asmagnesium, zinc, aluminum, silicon, and others.

A very material disadvantage of the use of catalysts in known processeslies in the inavoidable secondary reactions as incurred under theconditions of the standard pyrolytic processes that lead to theformation of oily polymerization products. These soon lower the activityof the catalysts so markedly that a reactivation is necessary, the oilypolymers poisoning the entire active surface of the catalyst. Additionalp'oisoning is caused by the formation of pyrolytic decompositionproducts due to the necessary high temperatures in standard crackingprocesses. Whereas the first inactivation is reversible, the second oneis irreversible, thus completely destroying the activity of that part ofthe catalysts.

It should also be stressed that in accordance with my present inventionit is necessary to use only a very small percentage of contact material.Contrary thereto, in all known processes of producing butadiene fromalcohols, reactions can be obtained only by use of great amounts ofrather expensive catalysts. Compared with such known processes, thepercentage of contact materials used during electron bombardment isextremely small, practically not more than a few percent of the amountof the rather expensive catalysts needed for the known methods. Inaddition thereto, it should be stressed that since the contact materialsused by me do not participate in the dehydrogenation and dehydrationreactions. occurring during electron bombardment, their life is muchlonger than that of the catalytically active catalysts used today in theknown processes.

Although I mentioned above as initial materials only alcohols,particularly ethyl alcohol, also other initial substances can bedehydrogenated and dehydrated so as to obtain butadiene. Thus, forinstance, in accordance with my present invention, it is possible to useas initial materials not only ethyl alcohol but also other aliphaticalcohols which, when treated as proposed above, form mono-olefines anddi-olefines, particularly butadiene, as well as per se highly valuablearomatic by-prcducts which in turn can also be electron bombarded againso as to be transformed also into butadiene. Of course, also othermaterials, such as propanol, iso-propanol. butanols,

dependent on the diiierent chemical characteror electron bombardmentemployed is preferably chosen so that each molecule of the initialmaterial is hit during bombardment by electrons having a total intensityof at least of a watt.

V As mentioned above, it is possible to use not only ethyl alcohol butalso other aliphatic alcohOiS and to subject the same to electronbomnardment causing dehydrogenation and dehyoration and formation ofbutadiene. Thus, for instance, dehydrogenation of 1,3-butylene glycol tobutadiene can be obtained by treatment with high speed electrons inpresence of contact material as described above. By this process. aparticularly pure butadiene is obtained which can be used directly forpolymerization purposes. This particular process will be of greatimportance wherever large amounts of acetylene, e. g. from natural gas.are available.

I wish to stress that it is also possible to use 2,:i-butylene glycol asinitial material. Bombarding such glycol with high speed electrons inthe presence of contact materials of the above described type, it ispossible to dehydrate the same to butadiene at room temperature in onestep with one recycling of unreacted glycol and to obtain yields ofbutadiene amounting to up to 85% of the theoretically maximum butadieneyield. Also in this case, the obtained butadiene is particularly easy topurify and can be obtained in better than 99% purity by one azeotropicdistillation. A detailed description of this process of obtainingbutadiene from glycol seems unnecessary since its details are the sameas those butadiene as described above.

It will be understood that each of the elements istics of the diii'erentinitial substances; however. I have found that the average intensitydescribed above, or two or more together, may

also find a useful application in other types of processes of producingbutadiene differing from the types described above.

While I have described the invention as embodied in processes ofproducing butadiene from various alcohols, I do not intend to belimitedto the details shown, since various modifications and changes may bemade without departing in any way from the spirit of my invention.

Without further analysis, the foregoing will so fully reveal the gist ofmy invention that others can by applying current knowledge readily adaptit for various applications without omitting features that, from thestandpoint of prior art, fairly constitute essential characteristics ofthe generic or specific aspects of this invention and, therefore, suchadaptations should and are intended to be comprehendsd within themeaning and range of equivalence of the following claims.

What I claim as new and desire to secure by Letters Patent is:

1. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by repeatedly bombarding itduring a series of consecutive very short periods with high speedelectrons of a velocity equivalent to more than one million volts,

6 thereby decomposing said alcohol and forming butadiene.

2. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by repeatedly bombarding itduring consecutive periods with high speed electrons of a velocityequivalent to more than one million volts, each or said consecutiveperiods lasting less than 10- of a second, thereby decomposing saidalcohol and forming butadiene.

3. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by subjecting it torepeated bombardments with high speed electrons of a velocity equivalentto more than 2 million volts, each of said electron bombardments lastingless than 10 of a second, thus decomposing said alcohol and formingbutadiene.

4. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by repeatedly bombarding itwith high speed electrons, each or said electron bombardments lastingless than 10" of a second, thereby decomposing said alcohol and formingbutadiene.

5. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by bombarding it during aseries of very short irradiation periods with high speed electrons inthe presence of a contact material not participating in the chemicalreaction caused by said electron bombardment but facilitating saidchemical reaction during said electron bombardment and retardingcontinuation of said chemical reaction after said electron bombardmenthas been discontinued.

6. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by repeatedly bombarding itduring a series of consecutive very short periods with high speedelectrons of a velocity equivalent to more than one million volts, eachof said consecutive periods lasting less than 10- of a second, in thepresence of a contact material not participating in the chemicalreaction caused by said electron bombardment but facilitating saidchemical reaction during said electron bombardment and retardingcontinuation of said chemical reaction after said electron bombardmenthas been discontinued, thereby decomposing said alcohol and formingbutadiene.

7. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by subjecting it torepeated bombardments with high speed electrons oi a velocity equivalentto more than 2 million volts, each of said electron bombardments lastingless than 10-- of a second in the presence of a contact material notparticipating in the chemical reaction caused by said electronbombardment but facilitating said chemical reaction during said electronbombardment and preventing continuation of said chemical reaction aftersaid electron bombardment has been terminated, thereby decomposing saidalcohol and forming butadiene.

8. Method of producing butadiene from ali phatic alcohol comprisingdehydrcgenating and dehydrating said alcohol by bombarding it during aseries of very short irradiation periods with high speed electrons insuch a manner that on the average each molecule of said alcohol is hit9. Method of producing butadiene from an allphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by bombarding it during aseries of very short irradiation periods with high speed electrons at atemperature of about 130 0., whereby said alcohol is in the gaseousphase during said electron bombardment.

10. Method of producing butadiene from an allphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by bombarding it during aseries of very short irradiation periods with h gh speed electrons inthe presence of a contact material selected from the group consisting ofoxide of metals of the second, third and fourth groups of the periodicsystem of elements, said contact material not participating in thechemi- -cal reaction caused by said electron bombardment butfacilitating said chemical reaction durmaterial selected from the groupof metals consisting of zinc, magnesium, aluminum, boron, calcium,strontium and silicon, said contact material not participating in thechemical reaction caused by said electron bombardment but facilitatingsaid chemical reaction during said electron bombardment and retardingcontinuation of said chemical reaction after said electron bombardmenthas been discontinued.

12. Method of producing butadiene from ethyl alcohol comprisingrepeatedly bombardng said ethyl alcohol with high speed electrons duringa series of very short irradiation periods thus dehydrogenating saidethyl alcohol to ethylene, and then repeatedly bombarding the thusformed ethylene again with high speed electrons during a series of veryshort irradiation periods, thus transforming said ethylene and formingbutadiene.

13. Method of producing butadiene from aliphatic alcohols comprisingdehydrogenat-ing and dehydrating said aliphatic alcohols by repeatedlybombarding them during consecutive periods with high speed elcctrons ofa velocity equivalent to more than one million volts, each of saidconsecutive periods lasting less than 10- of a second, in the presenceof a contact material not participating in the chemical reactioncausedbysaid electron bombardment but facilitating said chemicalreaction during'said electron bombardment and retarding continuation ofsaid chemical reaction after said electron bombardment has beendiscont'nued, thereby decomposing said aliphatic alcohols and formingbutadiene.

14. Method of producing butadiene from ethyl alcohol comprisingdehydrating and dehydrogenating said ethyl alcohol by bombarding thesame during a series of very short irradiation periods w'th high spezdelectrons at a temperature of between 130 and 160 (3., thus forming amixture comprising butadiene and aromatic compounds, and thereafterbombarding said aromatic compounds again repeatedly with high speedelectrons, thus transforming the same also into butadiene.

15. Method of producing butadiene from an aliphatic alcohol comprisingdehydrogenating and dehydrating said alcohol by repeatedly bombarding itduring consecutive periods with high speed electrons of a velocityequivalent to more than one million volts, each of said consecutiveperiods lasting less than 10 of a second, in the presence of a contactmaterial not participating in the chemical reaction caused by saidelectron bombardment but facilitating said chemical reaction duringsaid-\electron bombardment and retarding continuation of said chemicalreaction after said electron bombardment has been discontinued, therebyforming a reaction mixture comprising butadiene, removing said thusformed butadiene, and repeatedly bombarding the remaining reactionmixture during consecutive periods with high speed electrons of avelocity equivalent to more than one million volts. each of saidconsecutive periods lasting less than 10- of a second, thus decomposingsaid remaining reaction mixture and transforming the same also nearlyentirely into butadiene.

16. Method of producing butadiene from 1,3 butylene glycol comprisingdehydrogenating and dehydrating said 1.3 butylene glycol by subjectingit to repeated bombardments with high speed electrons of a velocityequivalent to more than 2 million volts, each of said electronbombardments lasting less than 10- of a second in the presence of acontact material not participating in the chemical reaction caused bysaid electron bombardment but facilitating said chemical reaction duringsaid electron bombardment and preventing continuation of said chemicalreaction after said electron bombardment has been terminated, therebydecomposing said 1.3 butylene glycol and forming butadiene.

17. Method of producing butadiene from 2,3 butylene glycol comprisingdehydrating said 2.3 butylene glycol by repeatedly bombarding it duringconsecutive periods with high speed electrons of a velocity equivalentto more than one million volts, each of said consecutive periods lastingless than 10- of a second, in the presence of a contact material notparticipating in the reaction caused by said electron bombardment butfacilitating said reaction during said electron bombardment andretardingcontinuation of said reaction after said electron bombardmenthas been discontinued, thereby decomposing said 2.3 butylene glycol andforming butadiene.

ARNO BRASCH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS OTHER REFERENCES Canadian Journal of Research, 4,pp. 470-481 (1931).

Ind. Eng. ChemQpages 1396-1398, Dec. 1931.

14. METHOD OF PRODUCING BUTADIENE FROM ETHYL ALCOHOL COMPISINGDEHYDRATING AND DEHYDROGENATING SAID ETHYL ALCOHOL BY BOMBARDING THESAME DURING A SERIES OF VERY SHORT IRRADIATION PERIODS WITH HIGH SPEEDELECTRONS AT A TEMPERATURE OF BETWEEN 130 AND 160*C., THUS FORMING AMIXTURE COMPRISING BUTADIENE AND AROMATIC COMPOUNDS, AND THEREAFTERBOMBARDING SAID AROMATIC COMPOUNDS AGAIN REPEATEDLY WITH HIGH SPEEDELECTRONS, THUS TRANSFORMING THE SAME ALSO INTO BUTADIENE.